1. Field of the Invention
The present invention relates to a transport system that transports semiconductor substrates or other articles via a carrier attached to an endless driving medium. In particular, the present invention relates to a technique of detecting a position of a carrier configured to carry articles such as semiconductor substrates or other articles, and driving a hand of a station.
2. Description of the Related Art
According to U.S. Pat. No. 7,234,584, a plurality of carriers are attached to an endless belt, and the endless belt rotates in a circulating manner. Each of the carriers has a support surface for supporting a flange or the like of a semiconductor cassette, and the cassette is loaded or unloaded using a hand of a station. Further, a sensor for detecting the carriers and an encoder for measuring moving distance of the belt are provided to control the hand. In U.S. Pat. No. 7,234,584, the hand is driven immediately after detection of the carrier by the sensor. Therefore, the hand is driven at the same timing in both of loading and unloading. However, if the hand is driven immediately after detection of the carrier, the delay in the signal processing appears as a control delay.